Manufacturing execution systems (MES) software can be a valuable tool for improving supply management, especially when paired with an ERP system. In this excerpt from Chapter 5 of the book Manufacturing Execution Systems (MES): Optimal Design, Planning, and Deployment, track materials and incoming goods and process warehousing costs.
Table of contents:
Using MES software to improve supply management planning and optimization
Tips for manufacturing production planning and scheduling with MES
5.3 Supply Management within the MES
5.3.1 Demand Planning
The central task of material requirements planning is to ensure material
availability through supply management. This means procuring
the necessary required quantities within the company and for sales at
the proper time.
This also includes monitoring stocks and in particular creating
procurement proposals for purchases. Here, demand planning strives
to find the optimal path between
- Best possible supply readiness and
- Minimization of costs and capital lockup
5.3.2 Material Requirement Calculation
As a first step, the planned resource requirements are calculated with
the aid of an operative planning forecast and coordinated with the
stock and availability situation. On this basis, decisions are made for
a reservation, for ordering, etc.
If data distribution is conducted in accordance with ISA guidelines
(see Sec. 3.2.1), work plans and therefore part lists are contained
in the MES. In order to be able to access the stock of all stock
types directly from supply management, stocks must be listed in
the MES.
5.3.3 Material Disposition in the MES or ERP System
In today's systems, material disposition generally takes place at level 4.
In future production management systems, production will plan in
the short-term on the basis of a real situation. New-order situations
can be calculated very quickly using the operative planning tools.
If orders must be made at short notice, the call-off order ideally is
sent to the supplier by an e-mail or is made directly available to the supplier
via a business-to-business (B2B) platform on the Internet. The
supplier transmits order confirmations and delivery dates in the same manner. Since the product data system will be managed at level 3 in
future systems, the latest data for work plans, together with their
parts lists, are always available to the planning department.
For calculating material requirements, required preliminary products
(articles) from in-house production also must be calculated and their
production planned. Based on the actual production order, "subcontracts"
can be generated automatically by the MES for production
of the preliminary products and assimilated into the sequence
planning.
5.3.4 Incoming Goods
In the incoming goods function, an incoming goods number is provided
automatically with reference to an open order. Then the individual
order positions are checked. Since deviations may arise during
quantitative checking of the delivery positions, the actual incoming
quantities, which are compared with the order quantity, should be
calculated. If an order has been made based on packing units, every
delivery unit should be recorded and managed according to stocks.
There may be some possible overlapping in quality management
in incoming goods inspections. In this case, a material booking should
be carried out via the MES. For every recorded delivery unit that is
brought into a warehouse, accompanying documents should be created
to facilitate identification of the goods.
If an incoming goods inspection in the sense of quality control is
needed for the material, this must be visualized through the MES.
Either a direct, on-the-spot inspection can be carried out or a laboratory
order can be generated automatically for the material. The material
is released for production only after positive inspection. For the
testing process, we refer to the inspection procedure used in production,
which generally agrees with the process in the incoming goods
section.
After the quantitative inspection and quality tests, material booking
must be transferred to accounting. Under certain circumstances,
specification of a cost center and a cost unit may be necessary.
5.3.5 Interaction between the ERP System and the MES
As we have shown, there is some overlapping of tasks between the
ERP system and the MES in terms of material management. In this
regard, there are various approaches for allocating these tasks:
- The best option is a service-oriented architecture (SOA). Here,
one tool, for example, the MES, uses the material booking of
another tool, in this case the ERP system, as a service. This
approach has defined interfaces and exchange formats. The
service is started through the handover of an ID with a corresponding
return value.
- Another suitable solution is saving the data using a data
warehouse. This allows for a global view of heterogeneous
and distributed data in which the data relevant for the global
view from the data sources are merged into a common, consistent
data set. Thus the content of a data warehouse arises
by copying and formatting data from different sources, in this
case an ERP system and an MES.
- The last option involves managing the tasks in two separate
tools. The result is that the data sometimes are saved in duplicate,
and therefore, more maintenance is required. Errors in data
management cannot be avoided.
5.3.6 Material Warehousing Costs
The quantity on stock (inventory) is to be assessed regarding accumulated
storage time using the warehousing cost rate. The resulting
warehousing costs are to be displayed. They must be available to the
MES for detailed planning and optimization. Inventory includes
stocks (raw material), stocks (semifinished goods), and stocks at production,
also known as work in process (WIP).
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